For organic EL elements, an organic electroluminescent element showing approximately 1000 cd/m2 at a drive voltage of 10 V or below has been reported, for example, by Tang et al., of Eastman Kodak Co., in 1987 (e.g. see Non-patent Document 1).
In order to enhance a luminous efficiency of element, Tang et al., tried optimization between an electrode and an organic compound, thereby making an organic electroluminescent element using an aromatic amine compound as a charge transporting layer and an aluminium complex of 8-hydroxyquinoline as an electron transporting light-emitting layer.
For a hole transporting material, there are known aromatic diamine derivatives (eg, see Patent Documents 1, 2 and 3), aromatic amine-containing polymers (e.g. Patent Documents 4 and 5) and the like. Specific examples include tetraphenylbiphenyldi amine (TPD), N-phenylcarbazole and 4,4′-[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB).
These materials, respectively, have a glass transition temperature of 60° C. to 95° C. and undergo crystallization by virtue of joule heat generated at the time of element drive, thereby causing element degradation. To avoid this, there is a demand for materials that have a high glass transition temperature and are stable.
Polymer materials have been used in some cases so as to increase a glass transition temperature, and polymer materials such as, for example, polyvinylcarbazole and the like are known as such a polymer material. However, elements using polymer materials such as polyvinyl carbazole and the like have the problem in that not only the drive voltage of the element is high, but also a life characteristic is poor. Accordingly, there has been a demand of polymer materials which can lower the element drive voltage and improve a drive life.
Non-patent Document 1:                Applied Physics Letters, Vol. 51. p 913, 1987        
Patent document 1:                Japanese Patent Laid-open No. Hei 8-20771        
Patent document 2:                Japanese Patent Laid-open No. Hei 8-40995        
Patent document 3:                Japanese Patent Laid-open No. Hei 8-40997        
Patent document 1:                Japanese Patent Laid-open No. Hei 11-283750        
Patent document 1:                Japanese Patent Laid-open No. 2000-36390        